Facebook adds 25% more stock to sell 2 days before IPO

Facebook shareholders are looking to pocket more cash as the big day inches closer

Facebook has, once again, updated its S-1 filing on Wednesday morning to add more shares to the Friday IPO.

While, earlier this week, the company added 50.6 million, this morning's update bumps it up another 25% to 421.2 million shares, which could raise an additional $3 billion to make the initial share sale worth as much as $16 billion.

If the company does end up selling its available share on Friday to the tune of $16 billion, it would be the largest tech IPO in history, and the third largest U.S. IPO ever, -- just following the $19.7 billion raised by Visa in March 2008, and the $18.1 billion raised by automaker General Motors in November 2010.

The company stated in the filing that the additional shares will be sold by selling shareholders of the company, not by the company itself, which will stick with previous plans to sell 180 million shares to the public.

CEO Mark Zuckerberg is not, however, selling any additional shares himself. He will still be selling 30 million shares -- around 6% of his Facebook holdings.

The share that Zuckerberg plans on selling are mostly to cover the exceptional tax bill he will be hit with -- which could top $1 billion.

Some early investors in Facebook are also increasing the number of shares would like to sell, including James Breyer of Accel Partners, who the largest shareholder other than Zuckerberg. Breyer is adding another 10.8 million shares to his selling ledger and now plans on offering 49 million shares, roughly 25% of his Facebook holdings.

Facebook was experiencing enough demand for its shares that the company increased the price range yesterday from $28-$35 to the now $34-$38 price range. The final pricing is expected after the market close Thursday, with shares to begin trading Friday morning.

DST Global, the fund run by Yuri Milner, is now selling 46 million shares -- up from 26.3 million.

Goldman Sachs is also selling more, increasing its stake sale to 28.7 million, more than twice the 13.2 million the investment bank had initially planned to sell.

Greylock Partners is now selling 7.6 million shares, up slightly from 7 million and Mail.ru Group Ltd is now selling 19.6 million, up from 11.3 million.

Tiger Global Management rocketed up the number of shares that it now intends to sell -- 23.4 million shares instead of just 3.4 million shares. It will now hold 2% of shares instead of 3% after planning to sell up to half its stake, instead of just 7%.

It could be that everyone is seeing this stock as having some serious action on the opening day, and want to get some liquidity while the payoff is clear and measurable.

I caught up with Founder and CEO of PrivCo, a financial research firm, Sam Hamadeh, and he explained that his company is placing a fair value price per share on the company at $25. This is due to the recent reports from the weak Q1 numbers and the mobile concerns from the company.

PrivCo also lowered its 2012 revenue estimate for Facebook from $5.41 billion to $5.367 billion and recommends selling the stock as long as it is at or above $25.

Perhaps these investors are getting similar advice and the $34-$38 range look like a sweet spot.